This invention relates to gas flares that operate on the Coanda principle. An exemplary such gas flare is shown in U.S. Pat. No. 4,634,372 issued Jan. 6, 1987. In such gas flares, a Coanda body is positioned across a flare stack to form an annular slot between the Coanda body and the pipe forming the gas conduit for the flare stack. The slot height is variable by use of springs within the flare stack to maintain a constant pressure in the flare stack. Such conventional flare stacks are subject to damage when a flame stabilizes on the surface of the Coanda body, and the springs are subject to damage and fouling by virtue of being exposed continuously to the corrosive and contaminated gases of the flare gas.